Otostegia persica (Lamiaceae): A review on its ethnopharmacology, phytochemistry, and pharmacology.

OBJECTIVE
The current study summarizes the updated information concerning the ethnopharmacology, Phytochemistry, and pharmacology of Otostegia persica Boiss. (Lamiaceae), an endemic medicinal plant in south and southeast of Iran.


MATERIALS AND METHODS
Information was collected through bibliographic investigation from scientific journals, books, theses, reports, and electronic search (databases SCOPUS, Google Scholar, Web of Science, and Science Direct). Moreover, documentation from unpublished resources and ethnobotanical surveys has been used. The present review covers the literature available from 2003 to 2013.


RESULTS
In traditional systems of medicine, this plant is reputed for treating diabetes, arthritis, gastric discomfort, headache, rheumatism, sedative activities, regulating blood pressure, and hyperlipidemia. Phytochemical screening of active components and mineral element evaluation of this species have been reported. Several types of diterpenoids and flavonols including morin, kaempferol, and quercetin are identified from the plant. Most of the pharmacological activity of this plant resides in its ﬂavonoid fraction which causes antimicrobial and antioxidant activities. Various pharmacological studies on O. persica show antimicrobial, antioxidant, anti-inflammatory, anti-diabetic, anti-aphid, and hepatoprotective activities.


CONCLUSION
Being an endemic plant of Iran, this species is an important medicinal herb which can be used for various purposes. This review might be helpful for scientists and researchers to find new chemical entities responsible for its claimed traditional uses and discover new lead compounds for diseases mentioned.


Introduction
Natural products have provided some of the important life saving drugs used in the armamentarium of modern medicine. However, among estimated 250,000-400,000 plant species, only 6% have been studied for biological activity and 15% have been investigated phytochemically. This shows the need for planned activity-guided Phytopharmacological evaluation of herbal drugs (Chaudhary et al., 2012).
Lamiaceae family is one of the largest and most distinctive families of flowering plants with about 220 genera and almost 4000 species worldwide (Naghibi et al., 2005;Víctor Benavides, 2010). Otostegia genus consists of about 33 species (Table 1) which grows mainly in the Mediterranean region and adjoining Asia Minor (Khan et al., 2009). In Iran, only three species are available, Otostegia aucheri, O. michauxi, and O. persica, of which the last two are endemic to Iran (Ayatollahi et al., 2009). Otostegia persica is called "Golder" locally (Yassa et al., 2005) and occurs mostly in dry tropical and subtropical habitats of Iran.
This article aims to provide an overview of the chemical constituents present in O. persica and ethnobotanical and pharmacological actions of this plant.  (Figure 1) (Bezenjania et al., 2012;Recshinger, 1982).
According to flora of Pakistan, O. persica is a shrub with dense glandular stems and suborbicular-obovate, cuneate leaves which have a prominent indumentum of glandular hairs and numerous sessile oil globules. They are creneate to dentate with spines which are present in axils of lower and upper leaves. Spiny bracts are horizontally spreading. Calyx being densely pilose, is 10-nerved or ribbed. Obovoid nutlets are rounded at apex and have oil globules with often only one maturing. (Ghahraman, 1994;Gahraman, 1996;Nasir and Ali, 1879).

Taxonomic Description
Taxonomic description of the plant is listed in Table 2.

Chemical Constituents
O. persica has a range of phytochemical compounds, of which only a few molecules are characterized, so complementary investigations are needed to identify new compounds in this species. Up to now, all investigations have been done on aerial parts of O. persica, for instance, Hajhashemi et al. (2004) reported the presence of flavonoids, steroids, tannins, and triterpenoids in O. persica, but up to now all steroids and triterpenoids are not fully reported in this plant. Some known components of the plant are summarized in Table 3 and are as follows:  Sharififar et al. (2007) analyzed the essential oil of flowers and fruits of O. persica. Alpha-pinene, 1-octen,3-ol cubenol are the main constituents of the flowers, while diisooctyl phthalate, and hexadecanoic acid are the major components of the essential oil obtained from the fruits. Sadeghi et al also reported caryophyllene oxide, β-sinesal and βcaryophyllene as major constituents of this species. In addition to caryophyllene oxide, Mahmoody identified verbenol in the essential oil. (Mahmoody, 2007). Geraniol, eugenol, ceryl alcohol, and hentriacontane are present in the essential oil isolated from O. persica by Ayatollahi et al. (Ayatollahi et al., 2007).

Phenolics
It has been shown that O. Persica contains flavonoids and tannins but it has no alkaloids and saponins (Mahmoody et al., 2007). Some of the important constituents of O. persica are flavonoids and phenolic compounds including morin, quercetin (Shrififar et al., 2003), kaempferol, and isovitexin (C-glucoflavone) as well as trans-Cinnamic acid which were identified from methanolic extract of O. persica by UV, IR, 1 H and 13 C NMR, and MS spectroscopies ( Figure 2) (Yassa et al., 2005). Caffeic acid, ρ-hydroxy benzoic acid, β-sitosterol, and βsitosteryl acetate were also identified in methanolic extract of O. persica (Ayatollahi et al., 2007).
Alone and in combination with similar phytosterols, β-sitosterol reduces blood levels of cholesterol and is sometimes used in treating hypercholesterolemia. β-sitosterol inhibits cholesterol absorption in the intestine (Matsuoka et al., 2008).

Terpenoids
Diterpenoids are another type of constituents which have been identified from the aerial parts of Otostegia persica. Ayatollahi et al. (2007) showed that dichloromethane extract of aerial parts of O. persica could be considered as a rich source of different terpenoids. Triterpene-related compounds such as β-amyrin, campesterol, and stigmasterol are also characterized in this species (Figure 3). Four known diterpenoids belonging to the clerodane and tetracyclic diterpene types were isolated for the first time from O. persica. These compounds are known to occur only in genus Otostegia ( Figure 4).

Mineral Composition
A number of essential minerals are found to be present in O. persica (Ayatollahi et al., 2007). Mineral elements including Ca, Mg, Na, Fe, K, Mn, Cr, Cu, Pb, and P were determined by spectroscopic methods for the first time by Sadeghi (2010) using two methods of sample preparation: dry ashing and microwave digestion.

Ethnobotanical uses or ethnopharmacology
The importance of O. persica is due to its wide variety of medicinal properties. Traditionally, plants belonging to this genus were used for a wide range of medicinal applications. O. persica has been widely used by Baluch people, who live in the southeast of Iran. People of this area use the aerial parts of this plant in the forms of decoction and infusion for treatment of headache, diabetes, stomachache, rheumatoid arthritis, toothache, and as anti-hyperlipidemia and analgesic. This species is also used for morphine withdrawal among Baluch people (Sadeghi, 2010;Javidnia, 2007, Naghibi et al., 2005Sadeghi et al., 2013). Safa et al. (2013) investigated that O. persica is commonly used for cardiac distress, reducing palpitation, regulating blood pressure, cough, headache, gastric discomfort, and parasite repellent as well as laxative, carminative, and antipyretic in south of Iran, Hormozgan province.

Pharmacological activities
To validate traditional claims associated with the genus, many studies have been carried out using various animal models and in vitro assays. These studies show that Otostegia species have a potential for developing remedial agents. Some major activities are described below:

Antimicrobial activity
Asghari et al. (2006)  Moreover, aqueous and organic extracts of this plant was evaluated for antifungal activity against 2 pathogenic fungus Aspergillus niger and Candida albicans. It was found that the highest inhibition was obtained with the ethyl acetate extract against Candida albicans (Asghari et al., 2006). Javidnia et al. (2009) showed that methanolic extract of O. persica is effective against specially gram positive bacteria (S. aureus and B. subtilis).

Anti-oxidant activity
The anti-oxidant activities of different extracts and fractions of aerial parts of O. persica were evaluated using beta-carotene bleaching and lipid peroxidation methods (Sharififar et al., 2003). The inhibitory activities of the plant extracts on the peroxidation of linoleic acid were measured using ferric thiocyanate method in comparison with methanolic extracts of green tea, Ginkgo biloba, vitamin E and BHA as positive controls. The results showed that methanolic extract of plant exhibited strong antioxidant activity. More investigation on methanolic extract showed that two compounds were responsible for antioxidant activity. Using UV, IR, MS, and ¹H and ¹³C NMR techniques, it was found that these two compounds were morin and quercetin (Shrififar et al., 2003) The antioxidant activity of the essential oils of O. persica was screened using two complementary test systems, i.e., DPPH free radical scavenging and ammonium thiocyanate. In both tested systems, essential oil of the flower exerted greater antioxidant and radical scavenging activity than essential oil of the fruit. In the first test, essential oil of flower exerted antioxidant activity with an IC 50 19.8±1.8 µg mL -1 almost similar to BHA and ascorbic acid (15. 2±1.1 and 17.4±1.3), respectively. In the ammonium thiocyanate system, the inhibition rate of oxidation of linoleic acid for essential oil of flower was estimated 93.5±2.8. The higher activity of this oil in comparison with essential oil of the fruit may be attributed to its high content of monoterpenes, especially oxygenated ones in the oil of the flower (Sharififar et al., 2007). This biological test for essential oils was also done by Tofighi et al. The IC 50 of the OSB essential oil was more potent (9.76±1.1) than natural and synthetic antioxidants such as vitamin E (12.02±1.8) and BHA (24.16±2.2) .
Metanolic extract of O. persica consists of flavonoids including morin, kaempferol, quercetin, and Isovitexin which might be responsible for antioxidant activity of the plant. Among these compounds, isovitexin showed the lowest activity which may be due to the absence of a hydroxyl at 3´ position. Comparing antioxidant activity of O. persica with Ginkgo biloba and green tea shows that its antioxidant potency is more than Ginkgo biloba and equal to green tea (Yassa et al., 2005;Adewole et al., 2007).

Anti-diabetic effect
O. persica is traditionally used in some regions of Iran as medicinal herb for antidiabetic properties. Thus, this activity is investigated by some research groups. In 2009, Tofighi et al. investigated anti-diabetic effect of O. persica. Anti-diabetic effect of this species on streptozotocin-diabetic rats was also investigated by Ebrahimpoor et al. and Manzari-Tavakoli et al., concluding that this plant had anti-hyperglycemic activity. Akbarzadeh et al. (2012) determined antidiabetic properties of O. persica in STZinduced diabetic rats and suggested it as a candidate drug for treating diabetes. They proposed that treatment with aqueous extract of O. persica would reduce insulin resistance, glucose and triglycerides concentrations, and increase the β-cells regeneration. They contributed this activity to flavonoid quercetin which has a similar effect as metformin, an anti-diabetic drug (Kannappan, 2009). Some studies show that anti-diabetic effect of quercetin on streptozotocin-induced diabetic rats is related to an increase in insulin absorption and glucose uptake (Cnop et al., 2005).

Anti-glycation activity
Diabetic pathogenesis is accompanied by increased glycation of proteins and accumulation of advanced glycation end products (AGEPs). Glycation and AGEP formation are also associated with the formation of free radicals via autoxidation of glucose and glycated proteins. O. persica has anti-glycation activity which is attributed to the presence of 3´,7-dihydroxy-4´,6,8trimethoxy-flavone ( Figure 5). In comparison with standard inhibitor rutin, which shows 83% inhibitory effect, this compound inhibits glycation 65% at 3 mM concentration (Ayatollahi et al., 2009;Ayatollahi et al., 2010). (Sulzer) as well as Tribolium castaneum (Herbst). The mortality percentage was significantly higher in A. fabae and M. persicae than in T. castaneum treatments.

Hepatoprotective activity
The hepatoprotective effect of the methanol extract of aerial parts (shoot) from O. persica has been investigated against the carbon tetrachloride (CCl4)-induced acute hepatotoxicity in male rats. Liver damage was assessed using biochemical parameters, i.e., plasma and liver tissue malondialdehyde (MDA), transaminase enzyme levels in plasma (aspartate transaminase (AST) and alanine aminotransferase (ALT)), and liver glutathione (GSH) levels. Results indicate that the methanol extract of O. persica shoot is active at 300 mg/Kg (per os) and possesses significant antioxidant and hepatoprotective activities. It is proposed that hepatoprotective mechanisms of this extract on CCl4-induced acute liver damage might be due to the decreased lipid peroxidation (decreased MDA level and increased content of GSH) (Mohammadi et al., 2012).

Toxicity
According to SCOPUS, Google Scholar, Web of Science, and Science Direct, no toxicity has been reported for this species.

Morphine withdrawal
Effect of O. persica on naloxone-induced morphine withdrawal syndrome was studied in male mice. Morphin withdrawal is associated with some signs including jumping, rearing, diarrhea, piloerection, tremor, and ptosis. While oral and i.p. administration of hydroalcoholic extract reduced the number of jumping and rearing, the hexane extract could not exert any significant change. Moreover, the hydroalcoholic extract (1500 mg/kg) significantly (p<0.05) reduced diarrhea, piloerection, tremor, and ptosis. The hexane extract only significantly (p<0.05) inhibited diarrhea. Both oral and i.p. administration of the hydroalcoholic extract reduced the number of jumping episodes in a dose dependent manner.
Intraperitoneal injection of hydroalcoholic extract was more effective than oral administration. Results of this study indicates that the extract of O. persica contains component(s) that alleviate morphine withdrawal syndrome and it is proposed that the responsible constituent(s) is (are) found in polar fraction, since the hexane extract have only a negligible effect. It is also proposed that this activity may be due to the flavonoid components of the plant. However, the active components and the mechanism of action of this plant are not known and further investigations are needed to clarify them (Hajhashemi et al., 2004).

Antimalarial activity
Antimalarial activity of O. persica and its combination with chloroquine against both CQ-sensitive and CQ-resistant strains of Plasmodium berghei was determined in 2012 by Nateghpour et al. (2012) via In-vivo fixed ratio method. First of all, ED 50 s were calculated. Determination of ED 50 s showed 1.1 mg/Kg and 2.4 mg/Kg of mouse body weight for chloroquine in CQ-sensitive and CQ-resistant strains, respectively, and 450 mg/Kg for O. persica in both strains. Results also showed that the combinations of "50% CQ + 50% OP", "30% CQ + 70% O.P" and "70% CQ + 30% OP" are more effective than other combinations against CQ-sensitive strain. Results suggest that O. persica potentiates the effectiveness of chloroquine against the chloroquine-sensitive strain of P. berghei but do not affect chloroquineresistant P. berghei.

Anti-arthritis
In arthritis, oxidation processes cause lipid peroxidation and formation of low-mass oligosaccharides resulting damage to bone and cartilage. Anti-oxidants are proposed as inhibitors of this process (Bors et al., 1996) and decrease the inflammation. Studies show that O. persica, due to the presence of flavonoids, has strong anti-oxidant activity. As a result, investigations suggest it as an anti-arthritis agent (Yassa et al., 2005).

Anti-inflammatory and healing of burn wound
Methanolic extract of the O. persica was newly investigated for accelerating healing process of burn wound. Results show that this extract significantly exhibited healing activity when topically applied on rats. O. persica is an effective treatment for saving the burn site (Ganjali et al., 2013).

Microscopic analysis
In 2010, microscopic analysis of aerial parts of O. persica was investigated by Tofighi et al. Results showed that O. persica powder had a pale yellowish-green color with little odor and bitter taste. The diagnostic characteristics are: (a) the covering trichomes (unicellular and multicellular) with wide base and sometimes warted walls, (b) The epidermis showing diacytic stomata, big cicatrix, spiral, double helix, and annular thickening vessels; some paranchymatous cells had beaded or sinuous walls, (c) The cluster crystals of calcium oxalate, and (d) the epidermal cells of the stigmas which were extended to form long and finger-like papillaes (Tofighi et al., 2010).
Otostegia persica has been explored exhaustively for its phytochemical, pharmacological, and ethnopharmacological activities. From the foregoing accounts, it is evident that O. persica plant has been used ethnomedicinally as a valuable therapeutic agent for a variety of diseases, as we have illustrated in this article. Various compounds which exist in this plant may be responsible for its pharmacological activities. More investigations are proposed for determining and discovering compounds responsible for its pharmacological activities.